Morbidity and mortality risks for chronic conditions such as cardiovascular disease, diabetes, hypertension, and stroke associated with overweight/obesity, physical inactivity, and unhealthy diets are higher in minority and economically disadvantaged women, who also tend to have poorer diet and physical activity behaviors compared to the general population. This study takes a comprehensive approach to behavior change that gives attention to individual attitudes and skills, sociocultural factors, and environmental factors influencing behavior change. The study's primary aim is to test the effects of 16 weeks of a culturally-appropriate, behavioral/social support lifestyle intervention (one counseling session and 16 weekly group sessions) on body weight, body mass index, and waist circumference, compared to a usual-care, minimal-contact control group (one counseling session) among overweight or obese women of lower income. The goal of the intervention is for the women (ages 25 to 50) to achieve a 10% reduction in weight at a rate of one to two pounds per week. Secondary aims are to: a) test the effects of the 16-week intervention on physical fitness, physical activity level, total energy intake, % caloric intake from total fat, saturated fat, and trans fat, fruit and vegetable intake, self-efficacy for diet and physical activity, social support for diet and physical activity, and behavioral skills for healthy diet and physical activity;b) test the effects of 8 weeks of a telephone-contact maintenance intervention on primary and secondary outcomes;and c) assess long-term maintenance of primary and secondary outcomes 18 weeks after the end of the maintenance intervention phase. Pre-intervention activities will include focus groups to insure cultural sensitivity of the intervention. A community advisory board will advise on recruitment, logistics, and cultural appropriateness. This community-based, randomized controlled trial will include 90 women in the intervention group and 90 in a "usual care" control group. Objective and self-report measures will be taken at four time points: baseline, immediate posttest after 16 weeks of intervention, delayed posttest after an additional 8 weeks of the telephone-contact maintenance intervention, and a follow-up posttest. To enhance community acceptability of the research, the control group will be offered the intervention after all measures are completed.